Process for the production of comminuted particles



Sept. 12, 1944. s. HILLER 2,358,068

PROCESS FOR THE PRODUCTION-OF COMMINUTED PARTICLES med Jan. s, 1941ATTORNEY Patented Sept.y 12, 1944 UNITED STATES 4PATENT .OFFICE PROCESSFOR THE PRODUCTION F COMBIINUTED PAR'IICLI'JS.

Siegfried` Hiller, New York, N. Y. Application January 3, 1941, SerialNo. `372,980 l 5 Claims;k

This invention relates to a process and-apparatus for the production ofcomminuted particles, in particular particles of metallic: oxides andrelated products, and includes correlated improvements designed toenhance the utility of such apparatus.

In my U. S. Patent No. 2,213,365 issued September 3, 1940, entitledApparatus for the production of powders of low-melting-point metals orof compounds thereof, I have described an apparatus including anatomizing chamber for producing flnely comminuted metallic particles.comminuted metallic particles which are thus formed pass directly intoan oxidizing chamber where the lighter particles become oxidized and aredrawn oil', While heavier particles fall back into the atomizingchamber.

It has now been found desirable to provide a process and apparatus forforming comminuted metallic particles of substantially uniform size anddiameter by providing for the disposal of the larger non-uniformparticles formed during the operation. It has also been found desirableto providel in such an apparatus means for separating the heavierparticles from the smaller particles and at the same time avoiding thedirect return of such heavier particles to the comminuting apparatus.

It is also desired to provide means for combining the smaller uniformmetallic particles with various gaseous reagents to form compounds orderivatives thereof and collect the same in a finely divided comminutedstate.

It is a general object of the present invention to provide a process andapparatus for the production of finely divided comminuted metallicparticles, oxides, or other compounds in a continuous operation.

It is a specic object of the present invention tov jects will in part beobvious and will in part appear hereinafter.

In carrying out the present invention it might be considered in itsbroadest aspects .as comprising two distinct embodiments.

vIn general, the process comprises comminuting molten metal, projectingthe comminuted particles into an atmosphere spaced from the point ofcomminution so that larger particles fall by gravity and are depositedat a point other than 'that of the point of comminution. v v In oneembodiment the process comprises melting a mass of metal, atomizing aportion thereof, separating-the larger particles from the'smallerparticles thus atomized, finally collecting the smaller uniformparticles while returning the larger particles to the original mass ofmolten metal.

A second embodiment of the invention contemplates further treatment ofthe finer particles,

comprising chemically reacting such particles `with various reagents toform compounds thereof,

and collecting such compounds in a substantially ilnely dividedcomminuted state.

In an apparatus suitable for carrying out the present invention there-is provided means for melting a low melting-point metal, means forcomminuting said metal to form comminuted metallic particles thereof,means for separating the heavier particles from the smaller and lighterparticles thus formed, means for returning said heavier particles to themolten metal, and means for collecting the lighter particles in a ilnelydivided state. l According to the present invention, there is alsoprovided in an apparatus for the production of v comminuted metallicvparticles orcompounds thereof, a vessel in which metal may be melted, acomminuting unit comprising a. rotatable ilinger wheel, a casing forsaid flinger wheel, 'an inlet in the bottom of said casing for admittingaportion of molten metal from the melting vessel, an outlet for saidcasing comprising a side duct and a combustion chamber connected to saidside duct, means for producing comminuted metallic particles in saidcomminuting unit and conveying said particles into the combustionchamber, collecting the lighter particles thus formed while returningthe heavier particles to said reservoir.

In a preferred embodiment there is also providedwithin said combustionchamber a reacti n 'z one for forming pure metallic particles, thetallic oxides, or various s other chemicalx compounds thereof, as saidfiner comminuted particles are being passed through said chamber.

Various low melting-point metals which may be employed to formcomminuted metallic particles comprise such metals as lead, tin,antimony, zinc,

y metals in the comminuted state to form various compounds thereofcomprise various reactive gases or vapors, such as air, steam or oxygenwhich form metallic oxides, sub-oxides, and the like. Other reactivegases such as chlorine, bromine, iodine, hydrogen sulfide, sulphur,carbon dioxide and the like may be used to form halides, suldes,carbonates and other compounds with the comminuted metals. Mixtures ofthese various gases may be used to form other derivatives of themetallic particles, and which also may depend upon operating conditions,such as temperature, pressure and the like.

Alternatively, suitable inert gases may be emv ployed toprevent theformation of compounds or derivatives of the various metals, forexample, such gases as helium, carbon monoxide, nitrogen, and otherinert gases. Such gases may be used to create an inert atmosphere toprovide for the formation of comminuted metallic particles in asubstantially unreacted state. Under other cond-itions hydrogen may beemployed either as a reactant to reduce metallic compounds-which may beformed, or to initially prevent the formation of such compounds. i

A suitable comminuting unit comprises such unit as described and setforth in my aforesaid U. S. Patent No. 2,213,365 and which will bedescribed in detail hereinafter.

For the combustion chamber there may be-employed any of a wide varietyof furnaces, burners or ovens which are used to burn the variousatomized or vaporized combustibles such as gases, fuel oil, powderedcoal, coke dust, and the like. In a preferred embodiment there isprovided a modied combustion chamber adapted to burn a gas, or toprovide other means for initiating a reaction between various gaseousreagents and the comminuted metallic particles causing them to ignite orotherwise combine to form compounds thereof. Alternatively, othermaterials such as inert gases may be introduced to prevent the formationof such compounds. Y,

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, theapparatus embodying features of construction, combinations andarrangement of parts adapted to effect such steps, and the product whichpossesses the characteristics, properties and relation of constituents,all as exemplified in the detailed disclosure hereinafter s, et4 forthand the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to vthe following detailed description taken inconnection with the accompanying drawing, in which: l

Fig. 1 is a view of a section in elevation of one form of apparatussuitable for carrying out the means of conduit I3 and utilized topreheat atomizing chamber I5.

The atomizing chamber I5 comprises a housing belt (not shown).

gases formed in furnace I0 may be drawn o by or casing I4 which ispreferably of an insulated type having a thick wall. In the bottom ofsaid atomizing chamber there is provided one or more openings I1 towhich there are attached tubes I8, which permit a portion of the moltenmetal I2 to enter the comminuting chamber by gravity flow. There isprovided in said atomizing chamber a flinger wheel I6 adapted to rotatewithin the atomizing chamber and which may be rotated by shaft 20. Theshaft may be driven by any suitable driving means, such as by beingcoupled directly to an electric motor or to a pulley and One side of theatomizing chamber `I5 is provided with an outlet duct I9 which is inturn connected with combustion cham ber 2 I, the lower portion 22 ofsaid chamber dipping into the surface of molten metal I2. Within thecombustion chamber 2| there is provided a plurality of jets or tuyres 23substantially near the central portion of said chamber, which jets areadapted to burn a light fuel, gas or oil if initial heat is founddesirable or necessary. In the preferred embodiment a combustible fuelor gas, such as water gas, hydrogen sulfide, or a halogen may beintroduced by means of supply pipes 24, and the jets 23 supplied with asuitable gas, such as air or oxygen, by means of pipes 26.Alternatively, a spark gap may be used in place of the flame jets; orreacting gases such as chlorine, hydrogen sulfide, and the like may beadmitted by means of the jets to form various metallic derivatives ofthe comminuted metallic particles; or such jets may be used to introducean inert gas. The air or other gases may be preheated by passing pipes26 through preheaters 21 comprising fire-brick surrounding thecombustion chamber and arranged about the reaction zone 3|.

Combustion chamber 2| is shown as having a constriction 3'I near the topportion, so that comminuted particles which are carried upwardly fromreaction zone 3| may be drawn off and/or burned in secondary burningzone 33. An excess volume of air may be admitted to the secondaryburning zone 33 by a draft created between dome 34 and collar 35, whichdraft intake is shown by direction arrows A. If desired, incompletecombustion reactions may be conducted with the metallic particles toform sub-oxides of the metals, or a mixture of pure metallic particlesand oxides thereof, or other various derivatives, by lowering or raisingthe dome 34 to admit larger or smaller volumes of air, as required.Alternatively, the dome may be lowered all the way, whereupon the domemakes a tight fit with collar 35, thus excluding air entirely. Thus airmay be excluded entirely from zone 33 when lt is desired to form themetal in comminuted metallic form, or when it is desired to form thesulfldes, chlorides, carbonates or metallic `deriva tives of the metalsother than the oxides. The particles may be drawn off by suitable knownmeans, such as by means of a draft created by a suction fan or blowerattached -to neck 32 (not shown).

Referring to Fig. 2, a portion of the combustion chamber is broken awayto show the flinger wheel I6 within casing I4 and to show itsrelationship with the combustion chamber 2|. Particles of the comminutedmetal are carried upwardly through the reaction zone 3|, which zone maybe supplied -with suitable gases by means of the jets 23 as described.The heavier particles formed during the comminuting process and whichare carried into the vertical chamber 2| are permitted to drop into thevessel Il by gravitational differoff or omitted entirely.

assaoee venting direct return o! the heavier particles to the atomizingchamber.

In carrying out the process of the invention. a suitable quantity ofmetal is melted in the melting vessel or reservoir," and after suihcientheating a quantity of the molten metal'is intro.- duced by gravity flowinto atomizing chamber I where it contacts the ilinger wheel IB. Theilinger wheel is rotated within the atomizing chamber at a velocitysuitable to create a mist comprising particles of said molten metal. Themajority of the particles thus formed iind their way or are driven outof the atomizing chamber through side duct |9-and into combustionchamber 2 I. It will be noted that vside duct I9 is closecoupled withthe combustion chamber 2| in order to facilitate the passage of thecomminutedpar ticles from the'atcmizlng chamber into the lower part ofthecombustion chamber.' A portion of the heavier particles formed duringthe atomizing process strike the inner wall 2S oi said chamber and dropdirectly into reservoir containing the molten metal. Other heavierparticles which may be carried along with the finely comminutedparticles gradually drop back into the reservoir il as the nnerparticles continu their upward travel through the combustion zone 3|,

where they may be ignited to form the various comminuted metallic oxidesor other compounds. Alternatively, the ignition jets 23 may be used tointroduce an inert gas or they may be closed In many cases after themetallic particles have been ignited for a short period of time andafter a suillcient temperature has been so maintained, the initialsupply oi fuel or gas introduced by jets 23 may be cut ofi:` and theburning of such metallic particles sustained by merely introducing intothe combustion chamber an adequate supply of prei heated air by means ofsupply pipes 26. Furthermore, other metallic particles, such as thoseformed of zinc or tin,.may become ignited and burn without the necessityof pre-ignition to initiate the combustion.

In a modification of the apparatus, a horizon- I tal combustion chambermay be substituted for the vertical combustion chamber illustrated inFig. 1, and blowing means may be utilized to disperse the comminutedparticles through such combustion chamber operated in conjunctionv with"the projecting means. k

The following exampleis given by way of illustrating the process of theinvention, but -is not to be interpreted in a limiting sense.

Substantially pure lead metal is melted in the melting vessel inquantity suilicient to flow into th'e atomizing chamber I5 by means ofopen-A ings I1 and contact the flinger wheel I6. The

is provided a striking plate formed of heavy metal removably attached tothe inner wall 2! which may be replaced from time to time as required.The remaining comminutcd metallic particles are carried upwardly throughthe cornbustion chamber, and leave the combustion chamber by means ofthe constricted portion 21 and are carried away by a reduced pressure`created within the dome 3l. 'As the particles travel upwardly throughthe combustion chamber 2| the remaining heavier lead particles areseparated from the iinely comminuted particles iiinger wheel is rotatedat a velocity suiiicient to create a mist comprising a plurality ofcomminuted particles of molten metal within the atomizing chamber I5.Preferably, the atomizing chamber is preheated by means of conduit I3 toprevent the particles from freezing against the walls of the atomizingchamber. The majority of the particles thus. formed find their way intothe vertical combustion chamber 2| by means 'of the outlet duct I9. Themajority by gravitational diierentiation and drop directly cinto the-vessel containing the molten lead by means of the open end portion 22.The finely comminuted lead particles are drawn ofi at 32 and collected.in known manner.

In the preferred embodiment the finely comminuted lead particles areignited in ignition zone 3|. Suitable ignition means for the burning ofsuch iinely divided lparticles is provided by the jets 23. Such ignitionis created by the introduction of a mixture of airand gas, such gascomprising a natural gas or methane. Burning is initiated by means ofair pipes 26 and gas pipes 24. As the finely divided lead particles areignited they are carried upwardly into a second ignition zone 33 wherefurther burning occurs. Suicient air to sustain the secondary burning ofthe particles is introduced between the dome 34 and collar 35, shown bydirection arrows A. The lead oxide thus formed is .drawn off at 32 in asubstantially iinely divided com-` minuted state. V

Alternatively, pure particles of lead of finely divided and uniform sizemay be formed by dropping the dome 34 to form a tight fit with collar 35and closing jets 23, or introducing an inert gas such as nitrogen in',place of the air and/or methane gas. The finely divided particles ofunreacted lead of size are then drawn oi at 32 as described placeciv-forming nely divided particles of'di/eafcted lead cr-lead oxides,lead sub-oxides maybe formed by introducing an insumcient supply of airor oxygen.

Lead sulides may be formed by admitting hydrogen sulnde to thecombustion zone 3| in place of air or oxygen. other lead compounds maybe formed in like manner by substituting other'v suitable gaseousreagents into the combustion chamber.

Among the advantages realized by the present invention, it will beobserved that by the gravitational return of the larger particles to thereservoir containing the molten metal the atomizing chamber is relievedof such rejected mateing out the above process and in the product.

and modications effected in the apparatus for of the heavier ccmminutedparticles strike the wall 29 of the combustion chamber and dropVpracticing the principle thereof without depart- 'i- Ving from thescope of the invention, it is inback into vessel |I containing themolten leadj. tended that all matter contained in the above In apreferred -embodiment (not shown) there 75. description or shown in theaccompanying draw- Chlorides, carbonates and' shall be interpreted asillustrative and not a limiting sense. It is'also to be understood thatthe following claims are intended to cover all of the generic andspecific features oi the invention herein described, and all statementsof the scope of the invention which, as a matter of language, might beslid t fall therebetween.

Having described my inventionl what I claim as new and desireto secureby Letters Patent is:

1. In a process for comminuting molten metal by beating and iiingingparticles of said molten metal into a gaseous atmosphere, theimprovement which comprises establishing a body of molten metal.coniining a portion of said molten metal in a restricted zonecommunicating with said body, beating said restricted portion tocomminute it and iiinging the comminuted metal particles into asubstantially vertically disposed iiue the lower end of which opens intosaid body o! molten metal at a region horizontally spaced freni saidrestricted zone, and establishing a regulated 'current of a gas in saidiiue sufficient to carry away smaller metal particles but which permitslarger particles to return to said body of molten metal by gravity.

2. In a process for comminuting molten metal by beating and ilingingparticles of said molten metal into a gaseous atmosphere, theimprovement which comprises establishing a body of molten metal,confining a portion of said molten metal in a restricted zonecommunicating with said body, beating said restricted portion tocomminute it and tlinging the comminuted metal particles into asubstantially vertically disposed flue the lower end of which opens intosaid body of molten metal at a region horizontally spaced from saidrestricted zone, and establishing a regulated current of a gas in saidue suiiicient to carry away smaller metal particles but which permitslarger particles to return to said body of molten metal by gravity,iinally collecting the smaller particles in a substantially solidifiedcomminuted state.

3.In a process for comminuting molten metal assaoos comminute itandfiiinging the comminuted metal particles into an inert gaseousatmosphere within a substantially vertically disposed flue the lower endof which opens into said body oi' molten metal at a region horizontallyspaced from said restricted zone. and establishing a regulated currentof said inert gas in said iiue sumcient to carry away smaller metalparticles but which permits larger particles to return to said body ofmolten metal by gravity.

4. In aprocess for comminuting molten metal by beating and fiingingparticles of said molten metal into a gaseous atmosphere, theimprovement which comprises establishing "a body of -molten metal,conning a portion of said molten metal ina restricted zone communicatingwith said body; beating said restricted portion to comminute it andinging the comminuted metal particles into a substantially verticallydisposed iiue the lower end oi' which opens into said body of moltenmetal at a region horizontally spaced from said restricted zone.chemically reacting the lsmaller particles with a gaseous reagent withinsaid iiue, and establishing a regulated current of a gas in said fluesuiiicient to carry away smaller chemically reacted metal particles butwhich -permits larger particles to return to said body of molten metalby gravity.

5. In a process for comminuting molten metal by beating and iiingingparticles of said molten metal into a gaseous atmosphere, theimprovement winch comprises establishing a body oi' Y molten metal,coniining a portion of said molten by beating and fiinging particles ofsaid molten metal in a restricted zone communicating with said body,beating said restricted portion to comminute it and flinging thecomminuted metal particles into a coniined zone within a iiue spacedfrom the point of comminution and having one end of said iiue openinginto said `body of molten metal at a region horizontally spaced fromsaid restricted zone, establishing a regulated current of gas in said uesufiicient to carry away the smaller comminuted particles but whichpermits larger particles to return to said body of molten metal bygravity, chemically reacting said smaller particles within said nue,whereby the said comminuted larger particles are return to said body ofmolten metal in a partially molten and substantially unreactedcondition.

SIEGFRIED HILLER.

